Fig. 1

Endoscopic, histopathological, immunohistochemical and in situ hybridization findings of the gastric tumors. A Endoscopic findings. The type IIc tumor is located in the gastric body near the fundus of the stomach (Triangle). The scale bar represents 1 cm. B Histopathological features of the AC component (accounting for 30%). Poorly differentiated tubular AC with focal glandular formation (Triangle, H&E; magnification, ×100, scale bar: 100 μm) and signet ring cell carcinoma (inset; H&E; magnification, ×400, scale bar: 20 μm). C Histopathological features of the SCC component (accounting for 40%). SCC component shows solid nest or trabecular proliferation of tumor cells with relatively rich eosinophilic cytoplasm and large round to oval nuclei (H&E; magnification, ×100, scale bar: 100 μm). Obvious keratinization was detected focally (inset; H&E; magnification, ×400, scale bar: 20 μm). D Histopathological features of the GCLS component (accounting for 30%). It is composed of irregular sheets, trabeculae, ill-defined tubules or syncytia of polygonal cells embedded within prominent lymphocytic infiltrate (H&E; magnification, x100, scale bar:100 μm; inset, magnification, x400, scale bar: 20 μm). E AB-PAS staining shows positivity in AC component (H&E; magnification, ×100, scale bar: 100 μm) and AB-PAS-positive mucus is noted in the tubular glands (inset, magnification, x400, scale bar: 20 μm). F Diffuse positive for p63 (H&E; magnification, ×100, scale bar: 100 μm) and for p40 (inset, magnification, ×400, scale bar: 20 μm) in SCC. G Positive for CK5/6 in SCC (H&E; magnification, ×100, scale bar: 100 μm) and negative in GCLS (inset, magnification, ×400, scale bar: 20 μm). H EBER is detected in GCLS (H&E; magnification, ×100, scale bar: 100 μm) and in AC with glandular formation (inset, magnification, ×400, scale bar: 20 μm). I EBER is diffuse positive in SCC (H&E; magnification, ×100, scale bar: 100 μm; inset, magnification, ×400, scale bar: 20 μm)